Vertical tube furnace



Sept. 8, 1959 J. w. THROCKMORTON- ET AL 2,902,981

VERTICAL TUBE FURNACE 2 Sheets-Sheet 1 Filed Sept. 20, 1957 INVENTORSSept. 8, 195 9 .1. w. THROCKMORTON ETAL 2,902,981

VERTICAL TUBEFURNACE Filed Sept. 20, 1957 2 Sheets-Sheet 2 INVENTORS Lu2,; JUH/V W THAUC/(MOKTO/V ATTOKA/f/ United States Patent Ofiice2,902,981 Patented Sept. 8, 1959 VERTICAL TUBE FURNACE John W.Throckmorton and John S. Wallis, New York,

N.Y., assignors to Petra-Chem Process Company, Inc'orporated, New York,N.Y., a corporation of Dela" ware Application September 20, 1957, SerialNo. 685,152

2 Claims. (Cl. 122-356) This invention relates to vertical tube heaterswhich are particularly adapted for very large capacity and in which thefluid to be heated may enter the heating tubes at temperatures as low at400 F., for example, and in which the desired outlet temperature fromthe radiant zone of the heater is at relatively high temperature suchas, for example, between 1400 to 1500 F.

One object of our invention is to have one bank of tubes in the radiantzone where the fluid temperature is relatively low exposed to directradiation from the burners on one side and one bank of tubes in theradiant Zone where the fluid temperature is relatively high exposed todirect radiation from the burners on both sides.

Qther objects and advantages of this invention will be apparent from thefollowing description and drawings showing certain embodiments of thisinvention, and from the appended claims.

Referring to the drawings:

Figure 1 is a partially sectional elevation of a vertical tube heaterembodying this invention.

Figure 2 is a sectional plan view taken on the line 22 of Figure 1.

Figure 3 is a detailed elevation on a larger scale illustrating one pairof heating tubes with a bottom guide and top supports.

Figure 4 is a sectional plan view on the line 44 of Figure 1.

Figure 5 is a plan view on a larger scale taken on the line 5-5 ofFigure 1.

Figure 6 and Figure 7 show on a smaller scale diagrammatic modificationswhich also embody this invention, these views corresponding generally tothe sectional plan view of Figure 5.

With special reference to Figs. 1 to 5, inclusive, the heaterillustrated comprises an upright cylindrical furnace shell 10,preferably formed of steel plate lined with a refractory or othersuitable heat insulating material.

The furnace shell 10 is supported by a plurality of structural beams 11,only two of which are shown in Fig. l, which extend to the top of thefurnace shell and project downwardly to the foundation 12 so as tosupport the shell and its bottom plate 13 at a sufficient height abovethe foundation to enable operators to have easy access to the bottom ofthe heater and to the burners 14 and 15 which are mounted therein. Thebottom plate 13 is provided with a door 16, which may be square as shownin Fig. 5, and provides access to the interior of the furnace.

An annular bridge wall mounted at the top of the furnace shell 10supports a square box 21. A plurality of brackets 22 are mounted uponand circumferentially spaced around the top of the furnace shell 10. Astack 23 is mounted on the brackets 22.

As shown in Fig. 5, the burners 14 are mounted in the form of a circleconcentric with the cylindrical furnace frame and approximately half waybetween the inner wall of the cylindrical furnace and the axis.

The burners 15 are also arranged in a circle but are spacedapproximately half way between the burners 14 and the wall of thecylindrical furnace. They are also spaced circumferentially a suificientdistance to permit certain of the heat exchange tubes to be installedbetween them, as hereinafter described.

While the heater described may be utilized for various sizes andcapacities, it is being built for commercial use with an inside diameterof the furnace shell of over 30 feet and with a height from thefoundation to the top of the box 21 of approximately feet.

Within the furnace a large number of vertical tubes 30 are located,spaced from but close to the inner insulating wall of the furnace shell.

Additional tubes 31 are arranged in radial banks between the bumers 15,as shown in Fig. 5. The tubes are interconnected at the bottom and topby the usual return bends and, as shown in Fig. 3, the return bends 32are used to connect the tubes 31 to each other and to the tubes 30 so asto form a desired number of coils. The tubes are supported laterally atthe bottom by lugs 54 which extend into holes 55 in the bottom plate 13of the furnace. All of the tubes are suspended from the bridge wall 20by hangers 56 which are connected to suitable lugs 57 mounted on thereturn bends at the top or on the L connections as shown in Fig. 3.

As shown in Fig. 5, for example, there are 18 coils, each made up offour wall tubes and two radial tubes. Each coil has an inlet connectionat the top of the furnace, as shown in Fig. 5, which connections aredesignated 33. Each inlet is connected through valve 34 and jumper 35 toone bank 36 of a preheating coil 37. The preheating coil 37 is made upof 18 vertical banks, as shown in Fig. 4, and each bank is connected toa fluid inlet manifold 40.

The fluid flows from the manifold 40 in multiple paths through the 18banks of the preheating coil 37 and into the several coils of largetubes which are interconnected, as already described, and the innermostradial tube of each coil is connected as shown in Fig. 1 by connections41 which extend upwardly inside the throat of the heater within thebridge wall 20 and radially inward to a large manifold 42.

The connections 41 of adjacent coils enter the mani fold 42 at twodifferent levels, asshown at 43 and 44 of Fig. 1. This enables the tubeends to be connected to the central manifold without crowding, as shownin Fig. 2.

Mounted within the furnace at the top and extending more than a third ofthe way from the top to the bottom of the furnace is an inverted conebaffle 50, which is suspended by hangers 51 from the bridge wall 20.

When the furnace is in operation, the oil, gas or other fluid to beheated is introduced through inlet pipe 52 into the manifold 43, thenceit flows through the flat coil banks 36 of the preheating coil 37. Fromeach bank 36 the fluid flows through its connector 35, valve 34,connector 33 and into the inlet pipe of one of the main coil banks,which is composed of four wall tubes 30 and two radial tubes 31, andthence through internal connections 41 to the manifold 42, and isdischarged out of the pipe 53. The fluid to be heated flows firstthrough the wall tubes, then through the radial tubes, which aresubjected to high temperature.

The burners 14 produce high temperature flame and hot gases which passupwardly through the furnace in an axial direction. The burners 15 alsoproduce hot flame and gases which pass upwardly through the furnace inan axial direction, with the result that radiant heat is supplied verydirectly to the wall tubes on their inner faces and is reflected to theback of the wall tubes by the insulating wall of the furnace shell 10.

The radial tubes 31 are arranged in staggered relation, as shown in Fig.5, so that they receive direct heat by radiation: on both sides from thetwo adjacent burners between'w-hich they are located.

The tubes in the radial banks, which for convenience have been referredto as radial tubes, may be made of special alloy metals, since. thefluid. has been: raised in temperature in passing through thepreheating; coil 37 andthroughthe wall tubes 30 before the fluidreachesthe radial tubes 31-;

The upper ends of the tubes are also heated to some extent*byconvection; because" theconical bafil'e' 50 re-' flects-thehot gases;which have already given'up part of their heat to-the fluid in thetubes, against the upper ends of the tubes, from thence the hotgasespass within the annular bridge wall 26 andfl'ow over theconnectionsReferring particularly to' Fig; 6, instead of providing 18 coils;the'heater may be divided, for example, into four coils-each composed of12' wall tubes and 3 radial tubes, and a' single burner 60" may besubstituted for burners 1*4 andthe four burners 61 may be substitutedfor the burners 15. The arrangement may be still further modified; asshown in Fig. 7, by using a singlecentral burner 65' and a ring ofburners 62', two of' which are located between each adjacent group ofradial tubes.

It is evident that further modifications maybe made within the spirit ofthis invention, and the number of coils'andthe arrangement will dependon the fluid to be heated, the size of the furnace, as well as numerousother factors, so that only such limitations should be imposed as areindicated in the appended claims.

What we claim is:

1. An upright furnace having a relatively tall cylindrical shell, a-fluegas exit at the top, a heat reflecting inner wall, a bottom plate, aplurality of radial banks of heat exchange tubes extending verticallyfrom top to bot-tom of the furnace shell, said radial banks extendingradially less than half the distance from the furnace wall 4* 7 towardthe central axis of the furnace, a plurality of circumferential banks ofheat exchange tubesextending from top to bottom of the furnace shelllocated between said radial banks near the furnace wall and spacedtherefrom, said circumferential banks together constituting a singlecylindrical row of heat exchange tubes spaced from the furnace wall andequally spaced from each other, upshot central burners-mounted in thebottom plate near the axis to discharge a column of flame and hot gaseswithin the open central space ofth'e' furnaceand an outer ring of upshotburners severally located to discharge flame and hot gases upwardly inthe spaces between the axial tube banks.

2. An upright furnace having a. relatively tall cylindrical shell, aflue gas exit at the top,, a heat reflecting inner wall, a bottom plate;a pluralityof radial banks of heat exchange tubes extending verticallyfrom top to bottom of the furnace shell, said radial banks extendingradially less" than half the distance from the'furnacewall toward thecentral axis of the furnace; a plurality of=circumferential banks ofheatexchange tubes extending from top to-bottomof the furnace shelllocated between said= radial banks near the furnacewall and spacedtherefrom, said circumferential banks together constituting a singlecylindrical row of heat exchangetnbes' spaced from the furnace wallandequally spaced frorrr each other; means for connecting each of thecircumferentialtube banks with an'adjacent radial bank at one end'toform a'plural ity of coils composed ofone-circumferenti'al an'dat*least-" one radial tube bank; upshot central burners'mountedin thebottomplate near the axis'to' dischargea' COIUHHI of flame and hot gaseswithin the'op'encentral space' of the furnace, and an outer' ring' ofupshot burners severally Wasp et: a1. A Dec. 1, 1953 UNITED STATESPATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,902,981 September8, 1959 John W. Throckmorton et al.

in the printed specification It is hereby certified that error appearsion and that the said Letters of the above numbered patent requiringcorrect Patent should read as corrected below.

Column 4, lines 13 and 35, strike out "axial", each occurrence, and

insert instead radial Signed and sealed this 15th day of March 1960.

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Commissioner of Patents AttestingOflicer

